The operational environment for a helicopter may include several different types of threats including but not limited to other aircraft, missiles and small arms fire. To operate and survive in this hostile environment, many helicopters are equipped with suites of advanced electronic sensor systems. For example, many helicopters are equipped with electronic warfare (EW) equipment, such as electronic support measures (ESM) or Radar Warning Receiver (RWR) systems, which detect radio frequency (RF) signals emitted by other aircraft and ground-based systems, and determine the characteristics of the detected RF signal (e.g., frequency, pulse repetition frequency (PRF), pulse width (PW), etc.). These EW systems may also determine the RF emitter type, operating mode of the RF emitter and provide visual or aural alerts or warnings to the aircrew indicating whether the detected RF signal is associated with a potential threat to the helicopter. However, because no RF signals are emitted by visually trained man portable weapons, such as AK-47s, the bullets fired from these weapons are not detected by these advanced sensor systems.
Many helicopters are also equipped with one or more countermeasure systems. Installed countermeasure systems, such as chaff and flares, protect the helicopter from heat seeking or radar guided weapons, by creating additional targets within the field of view (FOV) of the approaching missile. Coordinating the discharge of chaff and flares with extreme helicopter maneuvers causes the guidance system of the approaching missile, such as an infrared (IR) seeker or radar receiver, to miss the helicopter by causing the missile to become confused and lose the helicopter (i.e., break radar or IR tracking) in discharged chaff and flares.
Another type of countermeasure system used to counter IR-guided missiles is laser-based countermeasure systems, such as directional infrared countermeasure (DIRCM) system. DIRCM uses ultra-compact, solid-state, diode pumped lasers to transmit multiple laser lines in the mid-IR spectrum to jam virtually all currently fielded IR missiles. The DIRCM countermeasures system will be installed on slower-moving aircraft to autonomously detect, track and jam infrared threat missiles targeting them. However, none of the aforementioned countermeasure systems are effective against small projectiles, such as bullets, from visually trained small arms weapons.
Since helicopters typically operate at low altitudes and frequently hover or fly at low speed, bullets fired from visually trained small arms weapons pose a serious threat to helicopters, and can cause significant damage to helicopters, resulting in system failures, loss of the helicopter and the killing or maiming of the crew.
Hostile Fire Indicating (HFI) systems have been added to the equipment installed on many helicopters. HFI systems detect the presence of weapons being fired in the vicinity of the aircraft. HFI systems detect the firing of bullets or small projectiles either with optical sensors that detect the muzzle flash associated with the firing of a weapon, or with acoustic pressure sensors, such as piezoelectric transducers that detect the disturbance in the atmosphere created by the shock wave generated by the bullet or small projectile moving through the air. However, HFI systems are strictly limited to detecting the presence of small arms firing activity in the vicinity of the helicopter, providing a bearing of the location of the detected small arms firing from the helicopter, and providing a warning to the crew. HFI systems cannot counter the danger posed by small arms fire.
A laser-based system for countering the threat posed by visually trained small arms weapons has been proposed in recent years. The laser-based system transmits one or more laser beams to disrupt or interfere with the visual targeting capability of individuals firing small arms weapons (i.e., shooters). The capabilities of such a laser-based visual acquisition disrupter (or VAD) system are discussed in greater detail later in the specification.
The current VAD system prioritizes targets for engagement primarily based on two criteria: (a) the distance of the shooter from the helicopter; and (b) the most recent shooter to fire at the helicopter. This engagement prioritization scheme basically assigns higher priority to targets that are (a) closer in range (distance) to the helicopter and (b) the most recent to shoot at the helicopter (i.e., “last in—first out” (LIFO) time of last shot). However, the most recent shooter (i.e., LIFO time) or the shooter that is closest to the helicopter (i.e., shortest range) may not necessarily pose the greatest threat to the helicopter because small arms weapons vary in potential effectiveness against a helicopter based on many factors, including the size (i.e., caliber) of the fired projectile and muzzle velocity, rate of fire, and effective range of the weapon, for example. In addition, depending on the orientation of the helicopter with respect to the location of the shooter, the shooter closest to the helicopter in range may have the lowest probability of hitting the helicopter because of the high rate of angular change and small visible area of the helicopter with respect to the location of the shooter.
Therefore, since the current LIFO time and distance target engagement prioritization of the VAD system fails to assess the potential effectiveness, or lethality, of the threat posed by different weapons, it fails to adequately counter the visually trained small arms fire threat to the helicopter. More specifically, in a multiple threat environment, the LIFO time and distance target engagement prioritization of the current VAD system will fail to effectively counter the most effective (i.e., lethal) threats to the helicopter.
Therefore, what is needed is a system and method for controlling a VAD system to more effectively counter visually trained small arms threats to helicopters.